drivers/hwmon/max31790.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * max31790.c - Part of lm_sensors, Linux kernel modules for hardware
  *             monitoring.
  *
  * (C) 2015 by Il Han <corone.il.han@gmail.com>
  */

 #include <linux/err.h>
 #include <linux/hwmon.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/jiffies.h>
 #include <linux/module.h>
 #include <linux/slab.h>

 /* MAX31790 registers */
 #define MAX31790_REG_GLOBAL_CONFIG	0x00
 #define MAX31790_REG_FAN_CONFIG(ch)	(0x02 + (ch))
 #define MAX31790_REG_FAN_DYNAMICS(ch)	(0x08 + (ch))
 #define MAX31790_REG_FAN_FAULT_STATUS2	0x10
 #define MAX31790_REG_FAN_FAULT_STATUS1	0x11
 #define MAX31790_REG_TACH_COUNT(ch)	(0x18 + (ch) * 2)
 #define MAX31790_REG_PWM_DUTY_CYCLE(ch)	(0x30 + (ch) * 2)
 #define MAX31790_REG_PWMOUT(ch)		(0x40 + (ch) * 2)
 #define MAX31790_REG_TARGET_COUNT(ch)	(0x50 + (ch) * 2)

 /* Fan Config register bits */
 #define MAX31790_FAN_CFG_RPM_MODE	0x80
 #define MAX31790_FAN_CFG_CTRL_MON	0x10
 #define MAX31790_FAN_CFG_TACH_INPUT_EN	0x08
 #define MAX31790_FAN_CFG_TACH_INPUT	0x01

 /* Fan Dynamics register bits */
 #define MAX31790_FAN_DYN_SR_SHIFT	5
 #define MAX31790_FAN_DYN_SR_MASK	0xE0
 #define SR_FROM_REG(reg)		(((reg) & MAX31790_FAN_DYN_SR_MASK) \
 					 >> MAX31790_FAN_DYN_SR_SHIFT)

 #define FAN_RPM_MIN			120
 #define FAN_RPM_MAX			7864320

 #define FAN_COUNT_REG_MAX		0xffe0

 #define RPM_FROM_REG(reg, sr)		(((reg) >> 4) ? \
 					 ((60 * (sr) * 8192) / ((reg) >> 4)) : \
 					 FAN_RPM_MAX)
 #define RPM_TO_REG(rpm, sr)		((60 * (sr) * 8192) / ((rpm) * 2))

 #define NR_CHANNEL			6

 /*
  * Client data (each client gets its own)
  */
 struct max31790_data {
 	struct i2c_client *client;
 	struct mutex update_lock;
 	bool valid; /* zero until following fields are valid */
 	unsigned long last_updated; /* in jiffies */

 	/* register values */
 	u8 fan_config[NR_CHANNEL];
 	u8 fan_dynamics[NR_CHANNEL];
 	u16 fault_status;
 	u16 tach[NR_CHANNEL * 2];
 	u16 pwm[NR_CHANNEL];
 	u16 target_count[NR_CHANNEL];
 };

 static struct max31790_data *max31790_update_device(struct device *dev)
 {
 	struct max31790_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	struct max31790_data *ret = data;
 	int i;
 	int rv;

 	mutex_lock(&data->update_lock);

 	if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
 		rv = i2c_smbus_read_byte_data(client,
 				MAX31790_REG_FAN_FAULT_STATUS1);
 		if (rv < 0)
 			goto abort;
 		data->fault_status |= rv & 0x3F;

 		rv = i2c_smbus_read_byte_data(client,
 				MAX31790_REG_FAN_FAULT_STATUS2);
 		if (rv < 0)
 			goto abort;
 		data->fault_status |= (rv & 0x3F) << 6;

 		for (i = 0; i < NR_CHANNEL; i++) {
 			rv = i2c_smbus_read_word_swapped(client,
 					MAX31790_REG_TACH_COUNT(i));
 			if (rv < 0)
 				goto abort;
 			data->tach[i] = rv;

 			if (data->fan_config[i]
 			    & MAX31790_FAN_CFG_TACH_INPUT) {
 				rv = i2c_smbus_read_word_swapped(client,
 					MAX31790_REG_TACH_COUNT(NR_CHANNEL
 								+ i));
 				if (rv < 0)
 					goto abort;
 				data->tach[NR_CHANNEL + i] = rv;
 			} else {
 				rv = i2c_smbus_read_word_swapped(client,
 						MAX31790_REG_PWM_DUTY_CYCLE(i));
 				if (rv < 0)
 					goto abort;
 				data->pwm[i] = rv;

 				rv = i2c_smbus_read_word_swapped(client,
 						MAX31790_REG_TARGET_COUNT(i));
 				if (rv < 0)
 					goto abort;
 				data->target_count[i] = rv;
 			}
 		}

 		data->last_updated = jiffies;
 		data->valid = true;
 	}
 	goto done;

 abort:
 	data->valid = false;
 	ret = ERR_PTR(rv);

 done:
 	mutex_unlock(&data->update_lock);

 	return ret;
 }

 static const u8 tach_period[8] = { 1, 2, 4, 8, 16, 32, 32, 32 };

 static u8 get_tach_period(u8 fan_dynamics)
 {
 	return tach_period[SR_FROM_REG(fan_dynamics)];
 }

 static u8 bits_for_tach_period(int rpm)
 {
 	u8 bits;

 	if (rpm < 500)
 		bits = 0x0;
 	else if (rpm < 1000)
 		bits = 0x1;
 	else if (rpm < 2000)
 		bits = 0x2;
 	else if (rpm < 4000)
 		bits = 0x3;
 	else if (rpm < 8000)
 		bits = 0x4;
 	else
 		bits = 0x5;

 	return bits;
 }

 static int max31790_read_fan(struct device *dev, u32 attr, int channel,
 			     long *val)
 {
 	struct max31790_data *data = max31790_update_device(dev);
 	int sr, rpm;

 	if (IS_ERR(data))
 		return PTR_ERR(data);

 	switch (attr) {
 	case hwmon_fan_input:
 		sr = get_tach_period(data->fan_dynamics[channel % NR_CHANNEL]);
 		if (data->tach[channel] == FAN_COUNT_REG_MAX)
 			rpm = 0;
 		else
 			rpm = RPM_FROM_REG(data->tach[channel], sr);
 		*val = rpm;
 		return 0;
 	case hwmon_fan_target:
 		sr = get_tach_period(data->fan_dynamics[channel]);
 		rpm = RPM_FROM_REG(data->target_count[channel], sr);
 		*val = rpm;
 		return 0;
 	case hwmon_fan_fault:
 		mutex_lock(&data->update_lock);
 		*val = !!(data->fault_status & (1 << channel));
 		data->fault_status &= ~(1 << channel);
 		/*
 		 * If a fault bit is set, we need to write into one of the fan
 		 * configuration registers to clear it. Note that this also
 		 * clears the fault for the companion channel if enabled.
 		 */
 		if (*val) {
 			int reg = MAX31790_REG_TARGET_COUNT(channel % NR_CHANNEL);

 			i2c_smbus_write_byte_data(data->client, reg,
 						  data->target_count[channel % NR_CHANNEL] >> 8);
 		}
 		mutex_unlock(&data->update_lock);
 		return 0;
 	case hwmon_fan_enable:
 		*val = !!(data->fan_config[channel] & MAX31790_FAN_CFG_TACH_INPUT_EN);
 		return 0;
 	default:
 		return -EOPNOTSUPP;
 	}
 }

 static int max31790_write_fan(struct device *dev, u32 attr, int channel,
 			      long val)
 {
 	struct max31790_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	int target_count;
 	int err = 0;
 	u8 bits, fan_config;
 	int sr;

 	mutex_lock(&data->update_lock);

 	switch (attr) {
 	case hwmon_fan_target:
 		val = clamp_val(val, FAN_RPM_MIN, FAN_RPM_MAX);
 		bits = bits_for_tach_period(val);
 		data->fan_dynamics[channel] =
 			((data->fan_dynamics[channel] &
 			  ~MAX31790_FAN_DYN_SR_MASK) |
 			 (bits << MAX31790_FAN_DYN_SR_SHIFT));
 		err = i2c_smbus_write_byte_data(client,
 					MAX31790_REG_FAN_DYNAMICS(channel),
 					data->fan_dynamics[channel]);
 		if (err < 0)
 			break;

 		sr = get_tach_period(data->fan_dynamics[channel]);
 		target_count = RPM_TO_REG(val, sr);
 		target_count = clamp_val(target_count, 0x1, 0x7FF);

 		data->target_count[channel] = target_count << 5;

 		err = i2c_smbus_write_word_swapped(client,
 					MAX31790_REG_TARGET_COUNT(channel),
 					data->target_count[channel]);
 		break;
 	case hwmon_fan_enable:
 		fan_config = data->fan_config[channel];
 		if (val == 0) {
 			fan_config &= ~MAX31790_FAN_CFG_TACH_INPUT_EN;
 		} else if (val == 1) {
 			fan_config |= MAX31790_FAN_CFG_TACH_INPUT_EN;
 		} else {
 			err = -EINVAL;
 			break;
 		}
 		if (fan_config != data->fan_config[channel]) {
 			err = i2c_smbus_write_byte_data(client, MAX31790_REG_FAN_CONFIG(channel),
 							fan_config);
 			if (!err)
 				data->fan_config[channel] = fan_config;
 		}
 		break;
 	default:
 		err = -EOPNOTSUPP;
 		break;
 	}

 	mutex_unlock(&data->update_lock);

 	return err;
 }

 static umode_t max31790_fan_is_visible(const void *_data, u32 attr, int channel)
 {
 	const struct max31790_data *data = _data;
 	u8 fan_config = data->fan_config[channel % NR_CHANNEL];

 	switch (attr) {
 	case hwmon_fan_input:
 	case hwmon_fan_fault:
 		if (channel < NR_CHANNEL ||
 		    (fan_config & MAX31790_FAN_CFG_TACH_INPUT))
 			return 0444;
 		return 0;
 	case hwmon_fan_target:
 		if (channel < NR_CHANNEL &&
 		    !(fan_config & MAX31790_FAN_CFG_TACH_INPUT))
 			return 0644;
 		return 0;
 	case hwmon_fan_enable:
 		if (channel < NR_CHANNEL)
 			return 0644;
 		return 0;
 	default:
 		return 0;
 	}
 }

 static int max31790_read_pwm(struct device *dev, u32 attr, int channel,
 			     long *val)
 {
 	struct max31790_data *data = max31790_update_device(dev);
 	u8 fan_config;

 	if (IS_ERR(data))
 		return PTR_ERR(data);

 	fan_config = data->fan_config[channel];

 	switch (attr) {
 	case hwmon_pwm_input:
 		*val = data->pwm[channel] >> 8;
 		return 0;
 	case hwmon_pwm_enable:
 		if (fan_config & MAX31790_FAN_CFG_CTRL_MON)
 			*val = 0;
 		else if (fan_config & MAX31790_FAN_CFG_RPM_MODE)
 			*val = 2;
 		else
 			*val = 1;
 		return 0;
 	default:
 		return -EOPNOTSUPP;
 	}
 }

 static int max31790_write_pwm(struct device *dev, u32 attr, int channel,
 			      long val)
 {
 	struct max31790_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	u8 fan_config;
 	int err = 0;

 	mutex_lock(&data->update_lock);

 	switch (attr) {
 	case hwmon_pwm_input:
 		if (val < 0 || val > 255) {
 			err = -EINVAL;
 			break;
 		}
 		data->valid = false;
 		err = i2c_smbus_write_word_swapped(client,
 						   MAX31790_REG_PWMOUT(channel),
 						   val << 8);
 		break;
 	case hwmon_pwm_enable:
 		fan_config = data->fan_config[channel];
 		if (val == 0) {
 			fan_config |= MAX31790_FAN_CFG_CTRL_MON;
 			/*
 			 * Disable RPM mode; otherwise disabling fan speed
 			 * monitoring is not possible.
 			 */
 			fan_config &= ~MAX31790_FAN_CFG_RPM_MODE;
 		} else if (val == 1) {
 			fan_config &= ~(MAX31790_FAN_CFG_CTRL_MON | MAX31790_FAN_CFG_RPM_MODE);
 		} else if (val == 2) {
 			fan_config &= ~MAX31790_FAN_CFG_CTRL_MON;
 			/*
 			 * The chip sets MAX31790_FAN_CFG_TACH_INPUT_EN on its
 			 * own if MAX31790_FAN_CFG_RPM_MODE is set.
 			 * Do it here as well to reflect the actual register
 			 * value in the cache.
 			 */
 			fan_config |= (MAX31790_FAN_CFG_RPM_MODE | MAX31790_FAN_CFG_TACH_INPUT_EN);
 		} else {
 			err = -EINVAL;
 			break;
 		}
 		if (fan_config != data->fan_config[channel]) {
 			err = i2c_smbus_write_byte_data(client, MAX31790_REG_FAN_CONFIG(channel),
 							fan_config);
 			if (!err)
 				data->fan_config[channel] = fan_config;
 		}
 		break;
 	default:
 		err = -EOPNOTSUPP;
 		break;
 	}

 	mutex_unlock(&data->update_lock);

 	return err;
 }

 static umode_t max31790_pwm_is_visible(const void *_data, u32 attr, int channel)
 {
 	const struct max31790_data *data = _data;
 	u8 fan_config = data->fan_config[channel];

 	switch (attr) {
 	case hwmon_pwm_input:
 	case hwmon_pwm_enable:
 		if (!(fan_config & MAX31790_FAN_CFG_TACH_INPUT))
 			return 0644;
 		return 0;
 	default:
 		return 0;
 	}
 }

 static int max31790_read(struct device *dev, enum hwmon_sensor_types type,
 			 u32 attr, int channel, long *val)
 {
 	switch (type) {
 	case hwmon_fan:
 		return max31790_read_fan(dev, attr, channel, val);
 	case hwmon_pwm:
 		return max31790_read_pwm(dev, attr, channel, val);
 	default:
 		return -EOPNOTSUPP;
 	}
 }

 static int max31790_write(struct device *dev, enum hwmon_sensor_types type,
 			  u32 attr, int channel, long val)
 {
 	switch (type) {
 	case hwmon_fan:
 		return max31790_write_fan(dev, attr, channel, val);
 	case hwmon_pwm:
 		return max31790_write_pwm(dev, attr, channel, val);
 	default:
 		return -EOPNOTSUPP;
 	}
 }

 static umode_t max31790_is_visible(const void *data,
 				   enum hwmon_sensor_types type,
 				   u32 attr, int channel)
 {
 	switch (type) {
 	case hwmon_fan:
 		return max31790_fan_is_visible(data, attr, channel);
 	case hwmon_pwm:
 		return max31790_pwm_is_visible(data, attr, channel);
 	default:
 		return 0;
 	}
 }

 static const struct hwmon_channel_info *max31790_info[] = {
 	HWMON_CHANNEL_INFO(fan,
 			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
 			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
 			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
 			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
 			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
 			   HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT | HWMON_F_ENABLE,
 			   HWMON_F_INPUT | HWMON_F_FAULT,
 			   HWMON_F_INPUT | HWMON_F_FAULT,
 			   HWMON_F_INPUT | HWMON_F_FAULT,
 			   HWMON_F_INPUT | HWMON_F_FAULT,
 			   HWMON_F_INPUT | HWMON_F_FAULT,
 			   HWMON_F_INPUT | HWMON_F_FAULT),
 	HWMON_CHANNEL_INFO(pwm,
 			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
 			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
 			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
 			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
 			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
 			   HWMON_PWM_INPUT | HWMON_PWM_ENABLE),
 	NULL
 };

 static const struct hwmon_ops max31790_hwmon_ops = {
 	.is_visible = max31790_is_visible,
 	.read = max31790_read,
 	.write = max31790_write,
 };

 static const struct hwmon_chip_info max31790_chip_info = {
 	.ops = &max31790_hwmon_ops,
 	.info = max31790_info,
 };

 static int max31790_init_client(struct i2c_client *client,
 				struct max31790_data *data)
 {
 	int i, rv;

 	for (i = 0; i < NR_CHANNEL; i++) {
 		rv = i2c_smbus_read_byte_data(client,
 				MAX31790_REG_FAN_CONFIG(i));
 		if (rv < 0)
 			return rv;
 		data->fan_config[i] = rv;

 		rv = i2c_smbus_read_byte_data(client,
 				MAX31790_REG_FAN_DYNAMICS(i));
 		if (rv < 0)
 			return rv;
 		data->fan_dynamics[i] = rv;
 	}

 	return 0;
 }

 static int max31790_probe(struct i2c_client *client)
 {
 	struct i2c_adapter *adapter = client->adapter;
 	struct device *dev = &client->dev;
 	struct max31790_data *data;
 	struct device *hwmon_dev;
 	int err;

 	if (!i2c_check_functionality(adapter,
 			I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
 		return -ENODEV;

 	data = devm_kzalloc(dev, sizeof(struct max31790_data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	data->client = client;
 	mutex_init(&data->update_lock);

 	/*
 	 * Initialize the max31790 chip
 	 */
 	err = max31790_init_client(client, data);
 	if (err)
 		return err;

 	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
 							 data,
 							 &max31790_chip_info,
 							 NULL);

 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }

 static const struct i2c_device_id max31790_id[] = {
 	{ "max31790", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, max31790_id);

 static struct i2c_driver max31790_driver = {
 	.class		= I2C_CLASS_HWMON,
 	.probe_new	= max31790_probe,
 	.driver = {
 		.name	= "max31790",
 	},
 	.id_table	= max31790_id,
 };

 module_i2c_driver(max31790_driver);

 MODULE_AUTHOR("Il Han <corone.il.han@gmail.com>");
 MODULE_DESCRIPTION("MAX31790 sensor driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* max31790.c - Part of lm_sensors, Linux kernel modules for hardware
	* monitoring.
	*
	* (C) 2015 by Il Han <corone.il.han@gmail.com>
	*/

	#include <linux/err.h>
	#include <linux/hwmon.h>
	#include <linux/i2c.h>
	#include <linux/init.h>
	#include <linux/jiffies.h>
	#include <linux/module.h>
	#include <linux/slab.h>

	/* MAX31790 registers */
	#define MAX31790_REG_GLOBAL_CONFIG 0x00
	#define MAX31790_REG_FAN_CONFIG(ch) (0x02 + (ch))
	#define MAX31790_REG_FAN_DYNAMICS(ch) (0x08 + (ch))
	#define MAX31790_REG_FAN_FAULT_STATUS2 0x10
	#define MAX31790_REG_FAN_FAULT_STATUS1 0x11
	#define MAX31790_REG_TACH_COUNT(ch) (0x18 + (ch) * 2)
	#define MAX31790_REG_PWM_DUTY_CYCLE(ch) (0x30 + (ch) * 2)
	#define MAX31790_REG_PWMOUT(ch) (0x40 + (ch) * 2)
	#define MAX31790_REG_TARGET_COUNT(ch) (0x50 + (ch) * 2)

	/* Fan Config register bits */
	#define MAX31790_FAN_CFG_RPM_MODE 0x80
	#define MAX31790_FAN_CFG_CTRL_MON 0x10
	#define MAX31790_FAN_CFG_TACH_INPUT_EN 0x08
	#define MAX31790_FAN_CFG_TACH_INPUT 0x01

	/* Fan Dynamics register bits */
	#define MAX31790_FAN_DYN_SR_SHIFT 5
	#define MAX31790_FAN_DYN_SR_MASK 0xE0
	#define SR_FROM_REG(reg) (((reg) & MAX31790_FAN_DYN_SR_MASK) \
	>> MAX31790_FAN_DYN_SR_SHIFT)

	#define FAN_RPM_MIN 120
	#define FAN_RPM_MAX 7864320

	#define FAN_COUNT_REG_MAX 0xffe0

	#define RPM_FROM_REG(reg, sr) (((reg) >> 4) ? \
	((60 * (sr) * 8192) / ((reg) >> 4)) : \
	FAN_RPM_MAX)
	#define RPM_TO_REG(rpm, sr) ((60 * (sr) * 8192) / ((rpm) * 2))

	#define NR_CHANNEL 6

	/*
	* Client data (each client gets its own)
	*/
	struct max31790_data {
	struct i2c_client *client;
	struct mutex update_lock;
	bool valid; /* zero until following fields are valid */
	unsigned long last_updated; /* in jiffies */

	/* register values */
	u8 fan_config[NR_CHANNEL];
	u8 fan_dynamics[NR_CHANNEL];
	u16 fault_status;
	u16 tach[NR_CHANNEL * 2];
	u16 pwm[NR_CHANNEL];
	u16 target_count[NR_CHANNEL];
	};

	static struct max31790_data max31790_update_device(struct device dev)
	{
	struct max31790_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	struct max31790_data *ret = data;
	int i;
	int rv;

	mutex_lock(&data->update_lock);

	if (time_after(jiffies, data->last_updated + HZ) \|\| !data->valid) {
	rv = i2c_smbus_read_byte_data(client,
	MAX31790_REG_FAN_FAULT_STATUS1);
	if (rv < 0)
	goto abort;
	data->fault_status \|= rv & 0x3F;

	rv = i2c_smbus_read_byte_data(client,
	MAX31790_REG_FAN_FAULT_STATUS2);
	if (rv < 0)
	goto abort;
	data->fault_status \|= (rv & 0x3F) << 6;

	for (i = 0; i < NR_CHANNEL; i++) {
	rv = i2c_smbus_read_word_swapped(client,
	MAX31790_REG_TACH_COUNT(i));
	if (rv < 0)
	goto abort;
	data->tach[i] = rv;

	if (data->fan_config[i]
	& MAX31790_FAN_CFG_TACH_INPUT) {
	rv = i2c_smbus_read_word_swapped(client,
	MAX31790_REG_TACH_COUNT(NR_CHANNEL
	+ i));
	if (rv < 0)
	goto abort;
	data->tach[NR_CHANNEL + i] = rv;
	} else {
	rv = i2c_smbus_read_word_swapped(client,
	MAX31790_REG_PWM_DUTY_CYCLE(i));
	if (rv < 0)
	goto abort;
	data->pwm[i] = rv;

	rv = i2c_smbus_read_word_swapped(client,
	MAX31790_REG_TARGET_COUNT(i));
	if (rv < 0)
	goto abort;
	data->target_count[i] = rv;
	}
	}

	data->last_updated = jiffies;
	data->valid = true;
	}
	goto done;

	abort:
	data->valid = false;
	ret = ERR_PTR(rv);

	done:
	mutex_unlock(&data->update_lock);

	return ret;
	}

	static const u8 tach_period[8] = { 1, 2, 4, 8, 16, 32, 32, 32 };

	static u8 get_tach_period(u8 fan_dynamics)
	{
	return tach_period[SR_FROM_REG(fan_dynamics)];
	}

	static u8 bits_for_tach_period(int rpm)
	{
	u8 bits;

	if (rpm < 500)
	bits = 0x0;
	else if (rpm < 1000)
	bits = 0x1;
	else if (rpm < 2000)
	bits = 0x2;
	else if (rpm < 4000)
	bits = 0x3;
	else if (rpm < 8000)
	bits = 0x4;
	else
	bits = 0x5;

	return bits;
	}

	static int max31790_read_fan(struct device *dev, u32 attr, int channel,
	long *val)
	{
	struct max31790_data *data = max31790_update_device(dev);
	int sr, rpm;

	if (IS_ERR(data))
	return PTR_ERR(data);

	switch (attr) {
	case hwmon_fan_input:
	sr = get_tach_period(data->fan_dynamics[channel % NR_CHANNEL]);
	if (data->tach[channel] == FAN_COUNT_REG_MAX)
	rpm = 0;
	else
	rpm = RPM_FROM_REG(data->tach[channel], sr);
	*val = rpm;
	return 0;
	case hwmon_fan_target:
	sr = get_tach_period(data->fan_dynamics[channel]);
	rpm = RPM_FROM_REG(data->target_count[channel], sr);
	*val = rpm;
	return 0;
	case hwmon_fan_fault:
	mutex_lock(&data->update_lock);
	*val = !!(data->fault_status & (1 << channel));
	data->fault_status &= ~(1 << channel);
	/*
	* If a fault bit is set, we need to write into one of the fan
	* configuration registers to clear it. Note that this also
	* clears the fault for the companion channel if enabled.
	*/
	if (*val) {
	int reg = MAX31790_REG_TARGET_COUNT(channel % NR_CHANNEL);

	i2c_smbus_write_byte_data(data->client, reg,
	data->target_count[channel % NR_CHANNEL] >> 8);
	}
	mutex_unlock(&data->update_lock);
	return 0;
	case hwmon_fan_enable:
	*val = !!(data->fan_config[channel] & MAX31790_FAN_CFG_TACH_INPUT_EN);
	return 0;
	default:
	return -EOPNOTSUPP;
	}
	}

	static int max31790_write_fan(struct device *dev, u32 attr, int channel,
	long val)
	{
	struct max31790_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	int target_count;
	int err = 0;
	u8 bits, fan_config;
	int sr;

	mutex_lock(&data->update_lock);

	switch (attr) {
	case hwmon_fan_target:
	val = clamp_val(val, FAN_RPM_MIN, FAN_RPM_MAX);
	bits = bits_for_tach_period(val);
	data->fan_dynamics[channel] =
	((data->fan_dynamics[channel] &
	~MAX31790_FAN_DYN_SR_MASK) \|
	(bits << MAX31790_FAN_DYN_SR_SHIFT));
	err = i2c_smbus_write_byte_data(client,
	MAX31790_REG_FAN_DYNAMICS(channel),
	data->fan_dynamics[channel]);
	if (err < 0)
	break;

	sr = get_tach_period(data->fan_dynamics[channel]);
	target_count = RPM_TO_REG(val, sr);
	target_count = clamp_val(target_count, 0x1, 0x7FF);

	data->target_count[channel] = target_count << 5;

	err = i2c_smbus_write_word_swapped(client,
	MAX31790_REG_TARGET_COUNT(channel),
	data->target_count[channel]);
	break;
	case hwmon_fan_enable:
	fan_config = data->fan_config[channel];
	if (val == 0) {
	fan_config &= ~MAX31790_FAN_CFG_TACH_INPUT_EN;
	} else if (val == 1) {
	fan_config \|= MAX31790_FAN_CFG_TACH_INPUT_EN;
	} else {
	err = -EINVAL;
	break;
	}
	if (fan_config != data->fan_config[channel]) {
	err = i2c_smbus_write_byte_data(client, MAX31790_REG_FAN_CONFIG(channel),
	fan_config);
	if (!err)
	data->fan_config[channel] = fan_config;
	}
	break;
	default:
	err = -EOPNOTSUPP;
	break;
	}

	mutex_unlock(&data->update_lock);

	return err;
	}

	static umode_t max31790_fan_is_visible(const void *_data, u32 attr, int channel)
	{
	const struct max31790_data *data = _data;
	u8 fan_config = data->fan_config[channel % NR_CHANNEL];

	switch (attr) {
	case hwmon_fan_input:
	case hwmon_fan_fault:
	if (channel < NR_CHANNEL \|\|
	(fan_config & MAX31790_FAN_CFG_TACH_INPUT))
	return 0444;
	return 0;
	case hwmon_fan_target:
	if (channel < NR_CHANNEL &&
	!(fan_config & MAX31790_FAN_CFG_TACH_INPUT))
	return 0644;
	return 0;
	case hwmon_fan_enable:
	if (channel < NR_CHANNEL)
	return 0644;
	return 0;
	default:
	return 0;
	}
	}

	static int max31790_read_pwm(struct device *dev, u32 attr, int channel,
	long *val)
	{
	struct max31790_data *data = max31790_update_device(dev);
	u8 fan_config;

	if (IS_ERR(data))
	return PTR_ERR(data);

	fan_config = data->fan_config[channel];

	switch (attr) {
	case hwmon_pwm_input:
	*val = data->pwm[channel] >> 8;
	return 0;
	case hwmon_pwm_enable:
	if (fan_config & MAX31790_FAN_CFG_CTRL_MON)
	*val = 0;
	else if (fan_config & MAX31790_FAN_CFG_RPM_MODE)
	*val = 2;
	else
	*val = 1;
	return 0;
	default:
	return -EOPNOTSUPP;
	}
	}

	static int max31790_write_pwm(struct device *dev, u32 attr, int channel,
	long val)
	{
	struct max31790_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	u8 fan_config;
	int err = 0;

	mutex_lock(&data->update_lock);

	switch (attr) {
	case hwmon_pwm_input:
	if (val < 0 \|\| val > 255) {
	err = -EINVAL;
	break;
	}
	data->valid = false;
	err = i2c_smbus_write_word_swapped(client,
	MAX31790_REG_PWMOUT(channel),
	val << 8);
	break;
	case hwmon_pwm_enable:
	fan_config = data->fan_config[channel];
	if (val == 0) {
	fan_config \|= MAX31790_FAN_CFG_CTRL_MON;
	/*
	* Disable RPM mode; otherwise disabling fan speed
	* monitoring is not possible.
	*/
	fan_config &= ~MAX31790_FAN_CFG_RPM_MODE;
	} else if (val == 1) {
	fan_config &= ~(MAX31790_FAN_CFG_CTRL_MON \| MAX31790_FAN_CFG_RPM_MODE);
	} else if (val == 2) {
	fan_config &= ~MAX31790_FAN_CFG_CTRL_MON;
	/*
	* The chip sets MAX31790_FAN_CFG_TACH_INPUT_EN on its
	* own if MAX31790_FAN_CFG_RPM_MODE is set.
	* Do it here as well to reflect the actual register
	* value in the cache.
	*/
	fan_config \|= (MAX31790_FAN_CFG_RPM_MODE \| MAX31790_FAN_CFG_TACH_INPUT_EN);
	} else {
	err = -EINVAL;
	break;
	}
	if (fan_config != data->fan_config[channel]) {
	err = i2c_smbus_write_byte_data(client, MAX31790_REG_FAN_CONFIG(channel),
	fan_config);
	if (!err)
	data->fan_config[channel] = fan_config;
	}
	break;
	default:
	err = -EOPNOTSUPP;
	break;
	}

	mutex_unlock(&data->update_lock);

	return err;
	}

	static umode_t max31790_pwm_is_visible(const void *_data, u32 attr, int channel)
	{
	const struct max31790_data *data = _data;
	u8 fan_config = data->fan_config[channel];

	switch (attr) {
	case hwmon_pwm_input:
	case hwmon_pwm_enable:
	if (!(fan_config & MAX31790_FAN_CFG_TACH_INPUT))
	return 0644;
	return 0;
	default:
	return 0;
	}
	}

	static int max31790_read(struct device *dev, enum hwmon_sensor_types type,
	u32 attr, int channel, long *val)
	{
	switch (type) {
	case hwmon_fan:
	return max31790_read_fan(dev, attr, channel, val);
	case hwmon_pwm:
	return max31790_read_pwm(dev, attr, channel, val);
	default:
	return -EOPNOTSUPP;
	}
	}

	static int max31790_write(struct device *dev, enum hwmon_sensor_types type,
	u32 attr, int channel, long val)
	{
	switch (type) {
	case hwmon_fan:
	return max31790_write_fan(dev, attr, channel, val);
	case hwmon_pwm:
	return max31790_write_pwm(dev, attr, channel, val);
	default:
	return -EOPNOTSUPP;
	}
	}

	static umode_t max31790_is_visible(const void *data,
	enum hwmon_sensor_types type,
	u32 attr, int channel)
	{
	switch (type) {
	case hwmon_fan:
	return max31790_fan_is_visible(data, attr, channel);
	case hwmon_pwm:
	return max31790_pwm_is_visible(data, attr, channel);
	default:
	return 0;
	}
	}

	static const struct hwmon_channel_info *max31790_info[] = {
	HWMON_CHANNEL_INFO(fan,
	HWMON_F_INPUT \| HWMON_F_TARGET \| HWMON_F_FAULT \| HWMON_F_ENABLE,
	HWMON_F_INPUT \| HWMON_F_TARGET \| HWMON_F_FAULT \| HWMON_F_ENABLE,
	HWMON_F_INPUT \| HWMON_F_TARGET \| HWMON_F_FAULT \| HWMON_F_ENABLE,
	HWMON_F_INPUT \| HWMON_F_TARGET \| HWMON_F_FAULT \| HWMON_F_ENABLE,
	HWMON_F_INPUT \| HWMON_F_TARGET \| HWMON_F_FAULT \| HWMON_F_ENABLE,
	HWMON_F_INPUT \| HWMON_F_TARGET \| HWMON_F_FAULT \| HWMON_F_ENABLE,
	HWMON_F_INPUT \| HWMON_F_FAULT,
	HWMON_F_INPUT \| HWMON_F_FAULT,
	HWMON_F_INPUT \| HWMON_F_FAULT,
	HWMON_F_INPUT \| HWMON_F_FAULT,
	HWMON_F_INPUT \| HWMON_F_FAULT,
	HWMON_F_INPUT \| HWMON_F_FAULT),
	HWMON_CHANNEL_INFO(pwm,
	HWMON_PWM_INPUT \| HWMON_PWM_ENABLE,
	HWMON_PWM_INPUT \| HWMON_PWM_ENABLE,
	HWMON_PWM_INPUT \| HWMON_PWM_ENABLE,
	HWMON_PWM_INPUT \| HWMON_PWM_ENABLE,
	HWMON_PWM_INPUT \| HWMON_PWM_ENABLE,
	HWMON_PWM_INPUT \| HWMON_PWM_ENABLE),
	NULL
	};

	static const struct hwmon_ops max31790_hwmon_ops = {
	.is_visible = max31790_is_visible,
	.read = max31790_read,
	.write = max31790_write,
	};

	static const struct hwmon_chip_info max31790_chip_info = {
	.ops = &max31790_hwmon_ops,
	.info = max31790_info,
	};

	static int max31790_init_client(struct i2c_client *client,
	struct max31790_data *data)
	{
	int i, rv;

	for (i = 0; i < NR_CHANNEL; i++) {
	rv = i2c_smbus_read_byte_data(client,
	MAX31790_REG_FAN_CONFIG(i));
	if (rv < 0)
	return rv;
	data->fan_config[i] = rv;

	rv = i2c_smbus_read_byte_data(client,
	MAX31790_REG_FAN_DYNAMICS(i));
	if (rv < 0)
	return rv;
	data->fan_dynamics[i] = rv;
	}

	return 0;
	}

	static int max31790_probe(struct i2c_client *client)
	{
	struct i2c_adapter *adapter = client->adapter;
	struct device *dev = &client->dev;
	struct max31790_data *data;
	struct device *hwmon_dev;
	int err;

	if (!i2c_check_functionality(adapter,
	I2C_FUNC_SMBUS_BYTE_DATA \| I2C_FUNC_SMBUS_WORD_DATA))
	return -ENODEV;

	data = devm_kzalloc(dev, sizeof(struct max31790_data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	data->client = client;
	mutex_init(&data->update_lock);

	/*
	* Initialize the max31790 chip
	*/
	err = max31790_init_client(client, data);
	if (err)
	return err;

	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
	data,
	&max31790_chip_info,
	NULL);

	return PTR_ERR_OR_ZERO(hwmon_dev);
	}

	static const struct i2c_device_id max31790_id[] = {
	{ "max31790", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, max31790_id);

	static struct i2c_driver max31790_driver = {
	.class = I2C_CLASS_HWMON,
	.probe_new = max31790_probe,
	.driver = {
	.name = "max31790",
	},
	.id_table = max31790_id,
	};

	module_i2c_driver(max31790_driver);

	MODULE_AUTHOR("Il Han <corone.il.han@gmail.com>");
	MODULE_DESCRIPTION("MAX31790 sensor driver");
	MODULE_LICENSE("GPL");